For example, a common mode choke coil described in Japanese Patent No. 4209851 is known as a disclosure related to a conventional common mode filter. FIG. 12 is a cross-sectional structural view of a common mode choke coil 510 described in Japanese Patent No. 4209851.
The common mode choke coil 510 includes a main body 512, and coils 514, 516, 518. The coils 514, 516, 518 form a spiral shape spiraling clockwise from the outer circumferential side to the inner circumferential side when viewed from the upper side of the plane of FIG. 12 and overlap with each other. The coil 518 is interposed between the coil 514 and the coil 516 on both the upper and lower sides. In this common mode choke coil 510, a high-frequency signal is transmitted to the coils 514, 516, and a ground potential is connected to the coil 518.